function onOpen(){
  var ss = SpreadsheetApp.getActiveSpreadsheet();
  var subMenus = [];
  subMenus.push({name: "実行", functionName: "myFunction"});
  ss.addMenu("拡張", subMenus);
}

function myFunction() {
  sh = SpreadsheetApp.getActiveSheet();
  var mail_to = sh.getRange("A2").getValue();
  var subject = sh.getRange("B2").getValue();
  var body = sh.getRange("C2").getValue();
  var mail_cc = "akihiro.kobayashi@outlook.jp";
  MailApp.sendEmail(mail_to, subject, body, {cc: mail_cc});
  Browser.msgBox("メールを送信しました！");
}
